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Lookup NU author(s): Dr Chloe Start, Dr Catriona AndersonORCiD, Professor Angharad MR GatehouseORCiD, Dr Martin EdwardsORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
The endosymbiotic bacterium Buchnera aphidicola allows its host Acyrthosiphon pisum to utilise a nutritionally limited phloem sap diet without significant mortality by providing essential amino acids (EAAs), which it biosynthesises de novo via complex pathways consisting of multiple enzymes. Previous studies have reported how non-essential amino acids (NEAAs) provided by the host are utilised by B. aphidicola, along with how genes within the biosynthetic pathways respond to amino acid deficiency. Although the effect on B. aphidicola gene expression upon the removal of a single EAA and multiple NEAAs from the A. pisum diet has been reported, little is known about the effects of the complete simultaneous removal of multiple EAAs, especially branched-chain amino acids (BCAAs). To investigate this, A. pisum was provided with amino acid deficient diets ilv- (lacking isoleucine, leucine, valine) or thra- (lacking threonine, methionine, lysine). Due to their involvement in the production of several amino acids, the expression of genes ilvC, ilvD (both involved in isoleucine, leucine and valine biosynthesis) and thrA (involved in threonine, methionine and lysine biosynthesis) was analysed and the expression of trpC (involved in tryptophan biosynthesis) was used as a control. Survival was reduced significantly when A. pisum was reared on ilv- or thra- (P < 0.001 and P = 0.000 respectively) compared to optimal artificial diet and was significantly lower on ilv- (P < 0.001) than thra-. This is likely attributed to the EAAs absent from ilv- being required at higher concentrations for aphid growth, than those EAAs absent from thra-. Expression of ilvC and ilvD were upregulated 2.49- and 2.08-fold (respectively) and thrA expression increased 2.35- and 2.12-fold when A. pisum was reared on ilv- and thra- (respectively). The surprisingly large upregulation of thrA when reared on ilv- is likely due to threonine being an intermediate in isoleucine biosynthesis. Expression of trpC was not affected by rearing on either of the two amino acid deficient diets. To our knowledge this study has shown, for the first time, how genes within the biosynthetic pathways of an endosymbiont respond to the simultaneous complete omission of multiple EAAs as well as all three BCAAs (leucine, isoleucine, valine), from the host diet.
Author(s): Start CC, Anderson CMH, Gatehouse AMRG, Edwards MG
Publication type: Article
Publication status: Published
Journal: Journal of Insect Physiology
Year: 2024
Volume: 158
Print publication date: 01/10/2024
Online publication date: 07/08/2024
Acceptance date: 25/07/2024
Date deposited: 06/08/2024
ISSN (electronic): 0022-1910
Publisher: Elsevier
URL: https://doi.org/10.1016/j.jinsphys.2024.104683
DOI: 10.1016/j.jinsphys.2024.104683
Data Access Statement: Data will be made available on request
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